Chemometric tools in the optimization of a microwave-assisted digestion procedure for guarana-based drink samples and data analysis from elemental, caffeine, and epicatechin contents.

In this work, a method was developed for the determination of Na, K, Ca, Mg, P, S, Fe, Zn, Mn, and Cu by ICP OES and caffeine and epicatechin by HPLC-DAD in industrialized guarana-based beverages. The acid digestion in microwave oven was optimized by constrained mixture design. The optimum volumes found for the reagents were 2.60 mL (HNO3), 1.80 mL (H2O2), and 0.60 mL (HCl) for a final volume of 10 mL, resulting in a final digestate with residual acidity of 0.8 mol L-1 and 9% for residual carbon content. The detection limits found for the studied elements were between 0.0010 and 0.050 mg L-1. Precision (%RSD) was always below 6%. Accuracy was assessed by analyzing a certified reference material and addition and recovery tests. PCA and HCA were applied to caffeine, epicatechin and elemental concentrations aiming to evidence latent information.

Extraction induced by emulsion breaking for As, Se and Hg determination in crude palm oil by vapor generation-AFS.

In this work is presented the development of a method for As and Se determination in crude palm oil samples by hydride generation atomic fluorescence spectrometry and Hg by cold vapor atomic fluorescence spectrometry after ultrasound-assisted emulsification and extraction induced by emulsion breaking (EIEB). The optimization of the method was carried out by multivariate designs. The developed method has presented limits of quantification (LOQ) of 0.72, 0.12, and 1.5 µg L-1 for As, Hg, and Se, respectively. The precisions of the proposed method expressed as repeatability were 0.92, 2.2, and 3.7% RSD for 2 µg L-1 (n = 10) of As, Hg and Se, respectively. The developed methodology was applied in palm oil samples collected in the Bahia State. Concentrations (µg L-1) found in the samples were between

Analysis of metal contamination and bioindicator potential of predatory fish species along Contas River basin in northeastern Brazil.

Samples of two carnivore fish species (Hoplias malabaricus and Serrasalmus brandtii) were collected along Contas River, northeastern Brazil, to determine the levels of Co, Cr, Cu, Fe, Mn, Ni and Pb in edible and non-edible tissues of these important local fisheries resources. Lead could not be quantified in most of the samples, while the other metals were detected in both species. In edible parts, Cr levels were above Brazilian threshold limits in all specimens and Ni was at high concentration in S. brandtii individuals from one collection site. In non-edible parts (viscera), besides Cr, Cu concentration was higher than that recommended by Brazilian laws. Both fish species proved to be sensitive to environmental contamination. Despite the different ecological characteristics, such as vagility and feeding strategy, these fish showed that aquatic predators are efficient bioindicators of water quality and biomagnification.

Accumulation of trace metals in two commercially important shrimp species from Camamu Bay, Northeastern Brazil.

Camamu Bay is the second largest estuary in Bahia state, northeastern Brazil, being recognized by its high diversity and economical relevance for fisheries and tourism. To evaluate the impacts of environmental disturbances in Camamu Bay, trace metals (Cr, Mn, Fe, Co, Ni, Cu, and Pb) were quantified in two widespread and commercially exploited shrimp species (Farfantepenaeus paulensis and Xiphopenaeus kroyeri). High concentrations of all metals but Pb were observed in both species by ICPOES. The concentration values for Cr, Co, and Mn were invariably higher than the accepted limits for human consumption in Brazil. Inter and intraspecific variation in metal levels might be related to biological particularities and body size. The accentuated contamination by trace metals in both species validated them as efficient bioindicators of environmental quality. Thus, effective planning, monitoring and regulatory policies should be adopted to inspect and remediate the metal contamination in natural resources from Camamu Bay.